Agricultural harvesting machines such as combine harvesters generally are developed to handle a large variety of crops. For example a combine harvester may be used to harvest small grain crops such as wheat and rye, rape or grass seed or large grain crops such as peas or corn. In this manner the use of the harvester, which is a high investment tool, can be extended over a longer season.
Conventionally the harvester is equipped with a detachable crop collecting attachment, such as a grain or corn header, which cuts the stems of the crop standing in the field and conveys the same to the inlet of an elevator housing. Alternatively crop which has been cut previously can be lifted up from the field by a pick-up attachment and conveyed to the same inlet. An elevator apparatus, commonly a chain elevator with transverse slats, grab the collected crop deposited in front of the inlet and convey it rearwardly and upwardly towards the crop processing apparatus, conventionally a threshing drum and concave or grate assembly.
As illustrated by U.S. Pat. No. 3,758,472, the crop usually is engaged by the lower run of the chain elevator to transport it along a bottom plate of the elevator housing. The upper run is shielded from the lower run by a backing plate which extends between the front and rear transverse shafts of the elevator. This plate reduces the chances that material which was not removed from the elevator by the threshing system, falls back on top of the lower run and gets lodged between the chains and the sprockets driving the chains near the exit of the elevator. The backing plate equally provides additional support for the upper run of the chains.
When the machine is harvesting long-stemmed crops, the intermediate plate should extend forwardly as far as possible to ensure the return material is deposited in front of the conveyor.
When harvesting corn there is no immediate danger of stem material getting wrapped around the shafts of the elevator. Corn headers for combines usually have snaprolls for removing the corn ears (cobs) from the stems and the headers convey only these ears to the elevator entrance. Near the elevator outlet most of the ears are immediately grasped by the threshing apparatus, but some ears may escape and are engaged by the returning slats on top of the backing plate. These ears slide over the backing plate towards the front of the elevator, where they forcefully hit the so-called anti-dust plate which is installed at the front end of the elevator. The returning cobs cause premature wear and deformation of this front plate. It is an object of the invention to remedy thereto without compromising the proper operation of the conveyor during the harvest of small grains.
The operator needs easy access to the interior of the elevator housing, e.g. for removal or installation of the backing plate, for inspection and replacement of the elevator slats, for removal of stray material from the shafts, etc. Commonly, the top wall of the housing has an aperture which is closed by a cover or by a door, as illustrated in U.S. Pat. No. 3,981,125. Herein the door is connected by a hinge to the upper rim of the aperture. The size of the aperture is limited as the door has to swing open in the confined area below the steering platform. To provide additional access the top wall of the housing is provided with removable panels which are bolted onto housing frame. Such arrangement does not allow for a quick access to a larger portion of the elevator.